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PubMed2006

Genetic susceptibility to polyI:C-induced IFNalpha/beta-dependent accelerated disease in lupus-prone mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology. Associations between viral infections and the onset of SLE have been suggested, and recent studies have provided evidence that type I interferons (IFNalpha/beta) might play a role in the SLE disease process. Viruses and interferons have also been implicated in mouse models of SLE. We generated a model of accelerated proteinuria, in which lupus-prone mice were injected repeatedly with polyinosinic:polycytidylic acid (polyI:C), mimicking exposure to virus-derived double stranded RNA (dsRNA), leading to the production of IFNalpha/beta. PolyI:C-treated (B6.Nba2 x NZW)F1 and (B6 x NZW)F1 hybrid mice developed significantly increased levels of anti-dsDNA autoantibodies, characteristic of lupus. Most significantly, polyI:C-treated (B6.Nba2 x NZW)F1 mice, but not (B6 x NZW)F1 or parental strains, developed lupus-like nephritis in an accelerated fashion, which was dependent on IFNalpha/beta and associated with elevated deposition of total IgG, IgG2a and complement factor C3 in the glomerular capillary walls. These data suggest that reagents, which increase the levels of endogenous IFNalpha/beta (directly or indirectly), can accelerate the course of lupus-like nephritis, the development of which is dependent on the presence of both NZW- and Nba2-encoded genes.

Animals↗
PubMed1988

Host function of MAK16: G1 arrest by a mak16 mutant of Saccharomyces cerevisiae.

The MAK16 gene was first defined as a gene whose mutation resulted in loss of M1 double-stranded RNA virus-like particles. The mak16-1 mutation also produces temperature-sensitive cell growth. We report here that mak16-1 cells arrest at the nonpermissive temperature in G1 phase, such that they are mating competent. We sequenced the MAK16 gene and found an open reading frame of 306 amino acids encoding a predicted protein of Mr 35,694. Two typical nuclear localization signal sequences were found. MAK16-LacZ fusion proteins that include one of these putative signals entered the nucleus, while unfused beta-galactosidase did not, as judged by subcellular fractionation experiments. In the C-terminal third of the MAK16 open reading frame is an acidic region in which 25 of 41 residues are either glutamate or aspartate. This region contains potential phosphorylation sites for "casein kinases," protein kinases specific for serine or threonine residues in an acidic environment.

Base Sequence↗
PubMed1999

Host cell proteins bind specifically to the capsid-cleaved 5' end of Leishmaniavirus RNA.

Leishmaniavirus (LRV) is a double-stranded RNA (dsRNA) virus that persistently infects some strains of the protozoan parasite, Leishmania. LRV generates a short transcript, corresponding to the 5' end of the positive-sense RNA (320 nt), via a cleavage event mediated by the viral capsid protein on the full-length positive sense RNA transcript. To address the possibility that the RNA cleavage represents a regulatory mechanism for maintaining persistent infection, the interactions between Leishmania cytoplasmic proteins and in vitro synthesized viral transcripts were studied. In gel mobility shift experiments, three specific RNA/protein complexes were formed between cellular proteins and the cleaved viral transcript, and three major proteins were labeled by UV cross-linking. No protein binding activity was observed for either the short (320 nt) or full-length RNA transcripts. However, the two cleavage reaction products were able to form stable RNA/RNA complexes. We present a model in which the virus is targeting its own transcript for cleavage to promote binding of host factors to cryptic domains inaccessible in the full-length transcript.

5' Untranslated Regions↗
PubMed2000

Molecular characterization of the genome of a partitivirus from the basidiomycete Rhizoctonia solani.

The bisegmented genome of a double-stranded (ds) RNA virus from the fungus Rhizoctonia solani isolate Rhs 717 was characterized. The larger segment, dsRNA 1, is 2363 bases long whereas the smaller segment, dsRNA 2, has 2206 bases. The 5' ends of the coding strands of dsRNA 1 and dsRNA 2 are highly conserved (100% identity over 47 bases), and contain inverted repeats capable of forming stable stem-loop structures. Analysis of the coding potential of each of the two segments showed that dsRNAs 1 and 2 could code for polypeptides of 730 aa (bases 86-2275; molecular mass 86 kDa) and 683 aa (bases 79-2130; molecular mass 76 kDa), respectively. The 86 kDa polypeptide has all the motifs of dsRNA RNA-dependent RNA polymerases (RDRP), and has significant homology with putative RDRPs of partitiviruses from Fusarium poae and Atkinsonella hypoxylon. The 76 kDa protein shows homology with the putative capsid proteins (CP) of the same viruses. Northern blot analysis revealed no subgenomic RNA species, consistent with the fact that the long open reading frames encoding the putative RDRP and CP cover the entire length of the respective dsRNAs.

Amino Acid Sequence↗
PubMed1990

Interaction of interferons with skin reactive cytokines: from interleukin-1 to interleukin-8.

The skin as an organ contains a large pool of cells, important for the production of various cytokines. This study focuses on interferon-beta (IFN-beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) production by fibroblasts and epithelial cells in response to interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha). Both these primary cytokines show multiple biologic activities in the skin. Their antiviral activity on fibroblasts is mediated by IFN-beta and not by IL-6. In addition, TNF-alpha and IL-1 have a growth stimulatory effect on dermal fibroblasts, which is not mediated by IFN-beta or IL-6. IL-1, double-stranded RNA, or virus are potent inducers of IL-6 and IL-8 on dermal fibroblasts, but they are less efficient on epidermal cells. IL-8 has been discovered as an early acting skin reactive factor responsible for the chemotaxis of neutrophilic granulocytes. Furthermore, IL-1 possesses delayed skin reactivity upon intradermal injection which presumably is mediated by local release of IL-8. These findings demonstrate that cytokines also interact in the skin and that dermal fibroblasts play an important role in the regulation of aspecific host defense.

Cytokines↗
PubMed2002

Telomeric fingerprinting of the white root rot fungus, Rosellinia necatrix: a useful tool for strain identification.

The telomere associated DNA sequence pTel46, which was isolated from Coprinus cinereus, was hybridized with Rosellinia necatrix genomic DNA. The DNA fragments hybridized with pTel46 were more sensitive to Bal31 nuclease. This result suggests that the DNA fragments hybridized with pTel46 were located at the end of chromosomes in R. necatrix. Telomere-linked restriction fragment length polymorphism (RFLP) was found in strains of R. necatrix isolated from various field and single ascospores. Thus, this marker appears to be an excellent tool to show the great polymorphism of R. necatrix. However, RFLP could not be found among several field isolated strains belonging to the same mycelial compatibility group (MCG) isolated in the same field. Therefore the strains belonging to the same MCG might be the same strain that could be anastomosed with each other without cell death except for strain W718 carrying a double-stranded RNA (dsRNA) virus. Therefore the RFLP corresponded to a MCG group, and none of the strains belonging to the same MCG group showed different RFLP in R. necatrix. Moreover, the presence of a kind of dsRNA virus might imply anastomosis between compatible strains.

Ascomycota↗
PubMed1998

Interferon-inducible Mx proteins in fish.

Mx proteins are members of a family of interferon-inducible genes expressed when cells are treated with double-stranded RNA or virus infection. These proteins are important components of the antiviral response and form the first line of the body's defense against virus infections. The exact mechanism of action for these proteins has not been discovered, but mice missing the Mx genes are extremely sensitive to influenza virus infection. Mammals have between two and three Mx genes whose functions may vary with regard to the inhibition of a specific virus, cellular localization, and activity. The cDNA of three rainbow trout Mx proteins has been cloned and a comparison of their sequences with that of avian and mammalian species reveals striking conservation of domains. They all maintain the tripartite ATP/GTP binding domain and the dynamin family signature in the amino terminal half of the protein. In the carboxyl terminal half of the Mx proteins are the localization signals and the leucine zipper motifs which account for the trimerization of Mx in the cell. Like the rat and human Mx proteins, the different trout Mx proteins exhibit distinctly different immunohistochemical staining patterns in cells transfected with plasmids expressing RBTMx1, RBTMx2, or RBTMx3. To date, the antiviral function of the trout Mx proteins has not been satisfactorily established.

Amino Acid Sequence↗
PubMed1997

Detection of Colorado tick fever virus by using reverse transcriptase PCR and application of the technique in laboratory diagnosis.

Colorado tick fever (CTF) virus elicits an acute illness in humans, producing nonspecific flu-like symptoms and a biphasic fever in approximately 50% of patients. The disease is transmitted by the adult Rocky Mountain wood tick (Dermacentor andersoni), and therefore incidence is limited by the habitat and life cycle of that vector. The early symptoms of infection are difficult to distinguish from those of several other agents, especially Rickettsia rickettsii. Serologic testing is usually unable to provide evidence of CTF viral infection during the acute phase because of the late appearance of the various antibodies. Here we report the development and clinical application of a test to diagnose this disease during the acute stages. Oligonucleotide primers to the S2 segment of CTF (Florio) virus were made, and these were used in the amplification of a 528-bp fragment of DNA, transcribed from the double-stranded CTF virus RNA template by reverse transcriptase PCR. RNAs processed from 16 CTF virus isolates yielded similar results when analyzed on agarose gels. These were distinguishable from their antigenic relatives Eyach, S6-14-03, and T5-2092 and from other coltiviruses and an orbivirus but not from the antigenically distinct CTF virus-related isolate 720896. A mouse model demonstrated the utility of this method with whole-blood specimens, and CTF virus was successfully detected in human sera from the initial day of the onset of symptoms to 8 days later. The reverse transcriptase PCR method is a promising tool for the early diagnosis of CTF viral infection, or for ruling out CTF virus as the etiologic agent, in order to facilitate appropriate medical support.

Adult↗
PubMed1995

Brain- and intestine-specific variants of reovirus serotype 3 strain dearing are selected during chronic infection of severe combined immunodeficient mice.

Mutants of mammalian reoviruses, enteric double-stranded-RNA-containing viruses that spread systemically after primary replication in intestinal tissue, have been extensively studied as models of viral pathogenesis. While reovirus serotype 3 strain Dearing (T3D) causes acute encephalitis in newborn mice, adult severe combined immunodeficient (SCID) mice develop chronic infection with T3D, with some mice living more than 100 days after infection (B. L. Haller, M. L. Barkon, G. P. Vogler, and H. W. Virgin IV, J. Virol. 69:357-364, 1995). To determine whether organ-specific reovirus variants are selected during chronic infection, we characterized the pathogenetic properties of two variants of T3D isolated 87 days after intraperitoneal infection of adult SCID mice. A brain-specific variant (T3DvBr) (i) grew to a higher titer than T3D in SCID mouse brain (but not intestine) after intraperitoneal inoculation, (ii) killed adult SCID mice faster than T3D, and (iii) grew well in neonatal NIH Swiss [NIH(s)] mouse brain tissue after intramuscular but not peroral inoculation. An intestine-specific variant (T3DvInt) (i) grew to a higher titer than T3D in SCID mouse intestine (but not brain) after intraperitoneal inoculation, (ii) killed SCID mice with kinetics equivalent to those of T3D, (iii) was much less virulent than T3D in neonatal NIH(s) mice, (iv) grew better than T3D in intestines after intramuscular or peroral inoculation into neonatal NIH(s) mice, and (v) grew poorly in brain tissue of neonatal NIH(s) mice after intramuscular inoculation. During prolonged infection of SCID mice, organ-specific variants of T3D, which are more efficient than wild-type T3D at one specific stage in reovirus pathogenesis, are selected.

Animals↗
PubMedDate not supplied

Sleep, microbes and cytokines.

Dynamic changes in sleep in response to infectious challenge are a facet of the acute phase response. Changes in sleep induced by infection seem to be of recuperative value to the host. Furthermore, loss of sleep is associated with changes in immune function. Specific components of microbes such as muramyl peptides or endotoxin from bacteria or double-stranded RNA from virus induce sleep responses. These microbial-induced responses are mediated via enhanced cytokine and hormone production. Interleukin-1, tumor necrosis factor and interferon-alpha are somnogenic. Interleukin-1-enhanced sleep involves growth hormone-releasing hormone. Microbial-cytokine-altered sleep results from an amplification of physiological sleep mechanisms.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2025

MDA5 variants trade antiviral activity for protection from autoimmune disease.

Loss-of-function variants in MDA5, a key sensor of double-stranded RNA from viruses and retroelements, have been associated with protection from type 1 diabetes (T1D) in genome-wide association studies (GWAS). MDA5 loss-of-function variants have also been reported to increase the risk of inflammatory bowel disease (IBD). Whether these associations are linked or extend to other diseases remains unclear. Here, fine-mapping analysis of four large GWAS datasets shows that T1D-protective loss-of-function MDA5 variants also protect against psoriasis and hypothyroidism, while increasing the risk of IBD. The degree of autoimmune protection and IBD risk were linearly proportional. The magnitudes of the odds ratios for autoimmune protection and IBD risk were larger for rare MDA5 variants than for common variants, which were differentially expressed in different geographic populations. Our analysis suggests MDA5 genetic variants offer a direct fitness trade-off between viral clearance and autoimmune tissue damage.

Interferon-Induced Helicase, IFIH1↗
PubMed1992

Nuclear factor kappa B: an oxidative stress-responsive transcription factor of eukaryotic cells (a review).

NF-kappa B is a multiprotein complex that can activate a great variety of genes involved in early defence reactions of higher organisms. In nonstimulated cells, NF-kappa B resides in the cytoplasm in an inactive complex with the inhibitor I kappa B. Pathogenic stimuli cause release of I kappa B and allow NF-kappa B to enter the nucleus, bind to DNA control elements and, thereby, induce the synthesis of mRNA. A puzzling feature of NF-kappa B is that its activation is triggered by a great variety of agents. These include the cytokines interleukin-1 and tumor necrosis factor, viruses, double-stranded RNA, endotoxins, phorbol esters, UV light and ionizing radiation. We recently found that also low concentrations of H2O2 activate NF-kappa B and that various antioxidants prevent the induction by H2O2. Subsequent analysis revealed that antioxidants not only suppress the activation of NF-kappa B by H2O2 but by all other inducers tested so far. In this review, we will discuss the evidences that NF-kappa B is an oxidative stress-responsive transcription factor of higher eukaryotic cells.

Animals↗
PubMedDate not supplied

Report of a rotavirus outbreak in an adult nursing home population.

UNLABELLED: Rotavirus is a double-stranded RNA enteric virus that is the most important cause of severe, dehydrating diarrhea in infants and young children worldwide. Symptoms range from mild diarrhea to a life-threatening illness. Rotavirus occasionally afflicts adult members of the infected infant's family, geriatric patients, and immunocompromised hosts. We report the outbreak of rotavirus infection in a large nursing home facility. REPORT: In September 1996, 19 residents and 15 staff members of a 64-bed nursing home facility began to develop an acute, febrile illness associated with vomiting and diarrhea. The Public Health Service conducted an outbreak investigation. The infection displayed fecal-to-oral transmission with an incubation period of 1 to 2 days. The median duration of illness was 3 days for residents and 1 day for staff members. One resident died as a result of illness complications. Stool antigen tests from five residents and two employees were positive for rotavirus. Infection control policies were reevaluated, and interventions to arrest the outbreak were undertaken. The employee sick leave policy was strictly enforced. Education seminars were held, with employees reinforcing the concepts of enteric isolation and proper handwashing techniques. Surfaces and objects in the dining area were disinfected with a weak chloride solution. Once these measures were implemented, the rotavirus outbreak was contained. CONCLUSION: Rotavirus is a common cause of infectious diarrhea that can afflict the geriatric population. When infection occurs in a nursing home facility, rapid transmission can develop and morbidity can result. Nursing home infection control policies need to be evaluated constantly and new measures need to be implemented should an outbreak of rotavirus occur.

Journal Article↗
PubMed1979

Differential dependence of reovirus-associated enzyme activities on genome RNA as determined by psoralen photosensitivity.

Irradiation with long wavelength UV light in the presence of 4'-substituted psoralens abolished the in fectivity of reovirus and reovirus subviral particles Photoreaction of intact virions, cores, or genome RNA resulted in the formation of psoralen monoadducts and cross-links, demonstrating that the viral genome RNA in situ is double-stranded. Virus-associated RNA polymerase activity was lost following psoralen photoreaction, consistent with dependence on the genome RNA as template for viral mRNA synthesis. By contrast, reovirus guanylyl transferase and methyl transferase activities that catalyze the formation of mRNA 5'-terminal cap, m GpppG, were relatively unaffected by photoreaction. Cations that inhibit psoralen binding to nucleic acids also protected against loss of RNA polymerase activity. Partially photoinactivated viral cores produced decreased amounts of full length viral mRNAs. The absence of prematurely terminated transcripts indicates that template RNA modification by psoralen adducts has an all-or-none effect on initiation of mRNA synthesis by the core-associated RNA polymerase.

Cations, Monovalent↗
PubMed1982

A mode of action of RNase CI toward the various RNAs.

A mode of action of RNase CI toward the various native RNAs was examined. The mixture of tRNA from Thermus thermophilus HB8 were exhaustively cleaved by RNase CI to produce 90% of acid-soluble fraction. Among the minor nucleotides s2T were recognized by this enzyme. RNase CI generates a linear viroid molecule by introducing one single nick into viroid circular molecule. Double stranded RNA from RNA virus, such as Cytoplasmic polyhedrosis virus (CPV) from silk worm, was cleaved at some specific sites to produce more than ten of the discrete bands electrophoretically.

Animals↗